Why? Because that only works if you are absolutely certain that person has your number saved in their contacts.

Otherwise, your call looks exactly like spam, so either you will get ignored, or that person has to answer all calls from unknown numbers.

Anyone who would probably call me out of the blue that I might actually care about talking to is almost certainly in my contacts list. And I assume the converse is true. There are very few people who I'll just ring up to chat with. It's not really a big deal in that I can get the sense of a voice mail from the phone transcription pretty easily. But if I didn't catch someone and actually want to communicate something I'll probably follow up with a text.

> I assume the converse is true

I've made the same assumption and been wrong. It might be a bigger assumption than you realize. Maybe they just got a new phone, and their contact list wasn't synced correctly.